共查询到20条相似文献,搜索用时 15 毫秒
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ZHUJi-Zhen ZHOULi-Juan MAWei-Xing 《理论物理通讯》2005,44(1):117-122
Based on an extensively study of the Dyson-Schwinger equations for a fully dressed quark propagator in the “rainbow”approximation, a parametrized fully dressed quark propagator is proposed in this paper. The parametrized propagator describes a confining quark propagator in hadron since it is analytic everywhere in complex p2-plane and has no Lemmann representation. The validity of the new propagator is discussed by comparing its predictions on selfenergy functions A/(p2), Bl(p2) and effective mass M$(p2) of quark with flavor f to their corresponding theoretical results produced by Dyson-Schwinger equations. Our comparison shows that the parametrized quark propagator is a good approximation to the fully dressed quark propagator given by the solutions of Dyson-Schwinger equations in the rainbow approximation and is convenient to use in any theoretical calculations. 相似文献
3.
WU Kong-Ping SHI Yuan-Mei SUN Wei-Min PING Jia-Lun ZONG Hong-Shi 《理论物理通讯》2008,49(1):189-192
In quantum chromodynamics (QCD), the scalar susceptibility represents the modification of the quark condensate, to a small perturbation of the parameter responsible for the explicit breaking of the symmetry, i.e., the current quark mass. By studying the linear response of the dressed quark propagator to the presence of a nonzero quark mass, we derive a model-independent formula for the scalar susceptibility, which contains the dressed quark propagator G(p) and the dressed scalar vertex F(p, 0). The numerical values of the scalar susceptibility Xs are calculated within the framework of the rainbow-ladder approximation of the Dyson-Schwinger approach by employing two typical forms of model gluon propagator. 相似文献
4.
Meson corrections on the chiral condensate up to next-to-leading order
in a 1/Nc expansion
at finite density are investigated in the NJL model with explicit chiral symmetry breaking. Compared with mean-field results, the chiral phase transition is still of the first order while the properties near the critical density for chiral phase transition are found to change significantly. 相似文献
5.
Based on the quark propagator in the instanton dilute liquid approximation, we have determined the quark condensate , the mixed quark gluon condensate g,μνσμνq) and the four-quark condensate
at the mean-field level in the framework of global color symmetry model. The numerical calculation shows that our result is compatible with the range obtained within other nonperturbative approaches. In particular, we have found that even at the mean-field level the naive vacuum saturation approximation is not a good approximation when we consider nonlocal four-quark condensate. 相似文献
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ZONG Hong-Shi CHANG Lei HOU Feng-Yao SUN Wei-Min LIU Yu-Xin 《理论物理通讯》2005,44(3):519-524
Based on the rainbow approximation of Dyson-Schwinger equation and the assumption that the full inverse quark propagator at finite chemical potential is analytic in the neighborhood of μ = 1, it is proved that the dressed quark propagator at finite chemical potential μ can be written as G0^-1 [μ] =iγ·p↑-A(p↑-^2) +B(p↑-^2) with p↑-μ= (p↑-p4 +iμ). From the dressed quark propagator at finite chemical potential in Munczek model the bag constant of a baryon and the scalar quark condensate are evaluated. A comparison with previous results is given. 相似文献
8.
ZHOULi-Juan ZHUJi-Zhen MAWei-Xing 《理论物理通讯》2003,40(5):558-562
Based on Dyson-Schwinger equations in “rainbow” approximation, fully dressed confining quark propagator is obtained, and then the masses of light quarks (mu, md, and ms) are derived from the fully dressed confining quark propagator. At the same time, the local and non-local quark vacuum condensates as well as the quark-gluon mixed condensate are also predicted. Furthermore, the quark masses are also deduced from the Gell-Mann-Oakes-Renner relation and chiral perturbative theory. The results from different methods are consistent with each other. 相似文献
9.
Based on an extensive study of the Dyson-Schwinger equations for a fully
dressed quark propagator in the “rainbow” approximation, a parametrized form of the
quark propagator is suggested. The corresponding quark self-energy
Σf and the
structure of non-local quark vacuum condensate <0|:\bar{q}(x)q(0):|0>
are investigated. The algebraic form of the quark propagator proposed in this work describes a confining quark propagation, and is quite convenient
to be used in any numerical calculations. 相似文献
10.
Based on the quark propagator in the instanton dilute liquid approximation, we have determined the nonlocal four-quark condensate at the mean-field level in the framework of global color symmetry model. By making use of this formula, the vacuum susceptibility (pionsusceptibility) was calculated in this paper. The theoretical analysis and numerical calculation show that even at the mean-field level the naive vacuum saturation approximation is not a good approximation when we consider nonlocal four-quark condensate. 相似文献
11.
ZHOU Bang-Rong 《理论物理通讯》2005,44(5):879-882
We complete the derivation of the Cornwall-Jackiw-Tomboulis effective potentiM for quark propagator at finite temperature and finite quark chemical potential in the real-time formalism of thermal field theory and in Landau gauge. In the approximation that the function A(p^2) in inverse quark propagator is replaced by unity, by means of the running gauge coupling and the quark mass function invariant under the renormalization group in zero temperature Quantum Chromadynamics (QCD), we obtain a calculable expression for the thermal effective potential, which will be a useful means to research chiral phase transition in QCD in the real-time formalism. 相似文献
12.
According to extensive study of the Dyson-Schwinger equations for a fully dressed quark propagator in the "rainbow" approximation with an effective gluon propagator, a parametrized fully dressed confining quark propagator is suggested in this paper. The parametrized quark propagator describes a confined quark propagation in hadron, and is analytic everywhere in complex p2-plane and has no Lehmann representation. The vector and scalar self-energy functions [1 - Af(p2)] and [Bf(p2) - mf], dynamically running effective mass of quark Mf(p2) and the structure of non-local quark vacuum condensates as well as local quark vacuum condensates are predicted by use of the parametrized quark propagator. The results are compatible with other theoretical calculations. 相似文献
13.
D. Gromes 《The European Physical Journal C - Particles and Fields》2001,20(3):523-530
We decompose the quark propagator in the presence of an arbitrary gluon field with respect to a set of Dirac matrices. The
four-dimensional integrals which arise in first order perturbation theory are rewritten as line-integrals along certain field
lines, together with a weighted integration over the various field lines. It is then easy to transform the propagator into
a form involving path ordered exponentials. The resulting expression is non-perturbative and has the correct behavior under
Lorentz transformations, gauge transformations and charge conjugation. Furthermore it coincides with the exact propagator
in first order of the coupling g. No expansion with respect to the inverse quark mass is involved, the expression can even be used for vanishing mass. For
large mass the field lines concentrate near the straight line connection and simple results can be obtained immediately.
Received: 31 March 2001 / Revised version: 3 May 2001 / Published online: 8 June 2001 相似文献
14.
P. Chakraborty M.G. Mustafa M.H. Thoma 《The European Physical Journal C - Particles and Fields》2002,23(3):591-596
We calculate the quark number susceptibility in the deconfined phase of QCD using the hard thermal loop (HTL) approximation
for the quark propagator and quark–meson vertices. This improved perturbation theory takes into account important medium effects
such as thermal quark masses and Landau damping in the quark–gluon plasma. We explicitly show that the Landau damping part
in the quark propagator for space-like quark momenta does not contribute to the quark number susceptibility due to the quark
number conservation. We find that the quark number susceptibility only due to the collective quark modes deviates from the
free one around the critical temperature but approaches free results in the infinite temperature limit. The results are in
conformity with recent lattice calculations.
Received: 7 December 2001 / Published online: 15 March 2002 相似文献
15.
ZHOU Bang-Rong 《理论物理通讯》2005,44(11)
We complete the derivation of the Cornwall-Jackiw-Tomboulis effective potential for quark propagator at finite temperature and finite quark chemical potential in the real-time formalism of thermal field theory and in Landau gauge. In the approximation that the function A(p2) in inverse quark propagator is replaced by unity, by means of the running gauge coupling and the quark mass function invariant under the renormalization group in zero temperature Quantum Chromadynamics (QCD), we obtain a calculable expression for the thermal effective potential, which will be a useful means to research chiral phase transition in QCD in the real-time formalism. 相似文献
16.
A nonlocal chiral quark model is consistently extended beyond mean field using a strict 1/N c expansion scheme. It is found that the 1/N c corrections lead to a lowering of the temperature of the chiral phase transition in comparison with the mean-field result. On the other hand, near the phase transition the 1/N c expansion breaks down and a nonperturbative scheme for the inclusion of mesonic correlations is needed in order to describe the phase transition region. 相似文献
17.
A. Cabo Montes de Oca N. G. Cabo-Bizet A. Cabo-Bizet 《The European Physical Journal C - Particles and Fields》2009,64(1):133-145
A modified version of PQCD considered in previous works is investigated here in the case of retaining only the quark condensate.
The Green function generating functional is expressed in a form in which Dirac’s delta functions are now absent from the free
propagators. The new expansion implements the dimensional transmutation effect through a single interaction vertex in addition
to the standard ones in massless QCD. The new vertex suggest a way for constructing an alternative to the SM, in which the
mass and CKM matrices could be generated by the instability of massless QCD under the production of the top quark and other
fermions condensates, in a kind of generalized Nambu–Jona-Lasinio mechanism. The results of a two loop evaluation of the vacuum
energy indicate that the quark condensate is dynamically generated. However, the energy as a function of the condensate parameter
is again unbounded from below in this approximation. Assuming the existence of a minimum of the vacuum energy at the experimental
value of the top quark mass m
q
=173 GeV, we evaluate the two particle propagator in the quark–anti-quark channel in zero order in the coupling and a ladder
approximation in the condensate vertex. Adopting the notion from the former top quark models in which the Higgs field corresponds to the quark condensate, the results suggest that the Higgs particle could
be represented by a meson which might appear at energies around twice the top quark mass. 相似文献
18.
Guo-Ying Chen 《理论物理通讯》2018,70(6):683-688
We study the Nc scalings of pion-nucleon and nucleon-nucleon scatterings in hadron effective field theory. By assuming Witten's counting rules are applied to matrix elements or scattering amplitudes, which use the relativistic normalization for the nucleons, we find that the nucleon axial coupling gA is of order Nc0, and a consistent large Nc counting can be established for the pion-nucleon and nucleon-nucleon scatterings. We also justify the nonperturbative treatment of the low energy nucleon-nucleon interaction with the large Nc analysis and find that the deuteron binding energy is of order 1=Nc. 相似文献
19.
WANG Jing SHI Yuan-Mei HOU Feng-Yao SUN Wei-Min ZONG Hong-Shi PING Jia-Lun 《理论物理通讯》2008,49(4):1001-1003
We do a numerical calculation on the quark-loop effects on the dressed gluon propagator in the chiral limit. It is found that the quark-loop effects on the dressed gluon propagator are significant in solving the quark propagator in the rainbow approximation of the Dyson-Schwinger equation. The approach we used here is quite general and can also be used to calculate both the chemical potential and current quark mass dependence of the dressed gluon propagator. 相似文献
20.
Ken-ichi Konishi 《Nuclear Physics B》1977,131(1):143-171
Processes involving baryons are discussed in the scheme of dual unitarization. In particular, the topological expansion is generalized to any hadronic S-matrix elements involving baryons and/or mesons. Our expansion is based on a model for the baryon propagator, which is a set of three planar Feynman diagrams joined at a junction line. The resulting expansion is a double expansion in 1/N (N= the number of quark flavours) and in the number of baryon loops. Based on this, several new observations are made in phenomenological problems, and a unifying point of view is stressed. The scheme is evidently crossing invariant, and unitarity constraints are imposed order by order in 1/N and in the baryon loop number. 相似文献